feat: expand progression and multiplayer systems

Add named save slots, progression import/export, and a unified play flow. Add live friend requests, presence, invitations, and relationship controls without durable discovery-server social storage. Advance the network protocol with isolated channels, movement reconciliation, late-join recovery, fishing replication, and animation synchronization. Preserve per-species catch totals, refine generated-world startup and water recovery, and complete the related input and interface improvements.

tests/keyboard_mouse_mapping_validation.gd

@@ -28,6 +28,16 @@ func _run() -> void:
 		defaults.size()
 		== KeyboardMouseMappingManagerType.ROLE_ORDER.size()
 	)
+	assert(
+		not manager.get_binding(
+			KeyboardMouseMappingManagerType.ROLE_INTERACT
+		).is_empty()
+	)
+	assert(
+		manager.get_binding_label(
+			KeyboardMouseMappingManagerType.ROLE_INTERACT
+		) == "e"
+	)
 	assert(
 		str(defaults[
 			str(KeyboardMouseMappingManagerType.ROLE_PRIMARY_ACTION)
@@ -120,6 +130,11 @@ func _run() -> void:
 	interact_key.pressed = true
 	panel._input(interact_key)
 	assert(_has_physical_key(&"interact", KEY_F))
+	assert(
+		manager.get_binding_label(
+			KeyboardMouseMappingManagerType.ROLE_INTERACT
+		) == "f"
+	)
 	assert(not panel.is_capturing())
 
 	var settings_panel := SettingsPanelScene.instantiate() as SettingsPanel